An oblique joint of a conventional erectable manipulator can be folded up, and the manipulator can be disposed even in a narrow space. In order to realize a hollow oblique joint, a hollow harmonic drive reduction gear mechanism is provided (see Patent Document 1). Further, in order to drive the oblique joint, the power of a rotary axis of a motor to the speed-reduction mechanism is transmitted by a spur gear in a case where the rotation axis is parallel to the rotation axis of a joint, and is transmitted by a bevel gear in the case of inclination (see Patent Document 2).
FIG. 4 is a view showing a manipulator of Patent Document 1. In FIG. 4, 20 is an articulated manipulator, C1 is a first arm body, C2 is a second arm body, C3 is a third arm body, C4 is a fourth arm body, C5 is a fifth arm body, and C6 is a sixth arm body. The arm bodies are connected together so as to be rotatable around the rotation axes tilted at 45 degrees. In the articulated manipulator 20, the position and posture of a hand apparatus that are provided at the sixth arm body C6 (not shown) can be changed by rotating the arm bodies C1 to C6, respectively. Further, the first arm body C1 and the second arm body C2, the second arm body C2 and the third arm body C3, the third arm body C3 and the fourth arm body C4, and the fifth arm body C5 and the sixth arm body C6 are bent at 90 degrees with respect to each other. From this posture, if the second arm body C2 is operated with respect to the third arm body C3, and the fourth arm body C4 is operated with respect to the third arm body C3, the position of the sixth arm body C6 can be kept away from the first arm body C1 in the lateral direction Y, and can be made small in the height direction Z. This enables the sixth arm body C6 to be moved in the lateral direction Y in a state where the posture of the sixth arm body C6 is maintained, and the distance in the longitudinal direction Z between the sixth arm body C6 and a base 21 is short. As such, the oblique joint of the conventional manipulator can be folded up, and the manipulator can be disposed even in a narrow space. Further, FIG. 5 is a view showing a joint mechanism of a robot according to Patent Document 2. In FIG. 5, the rotation of a motor 12 drives an oblique joint 6 via bevel gears 40 and 42. As such, the oblique joint of the conventional manipulator drives joints via a gear device.    Patent Document 1: JP-A-2004-148449    Patent Document 2: JP-A-2003-025269